Sound deadener



May '5, 1942. H. vAN TONGEREN S OUND DEADENER Filed April l5, 1941 J mgm.

Patented May 5,1942

SUND BEADENER Hel-marinus van Tongeren, Heemstede, Netherlands Application April 15, "i941, SerialvfNo. 388,709 En the Netherlands May 8, 1940 4i Claims.

This invention relates to a sound-deadener for i a gas conduitfior instance the exhaust conduit of an internal combustion engine, having the usual circular, or an elliptical cross-section.

Known sound-deadeners comprise a plurality of rectangular flat plates of sound absorbing material and arranged in spaced parallel relation to each other and to the axis of the conduit. This arrangement necessitates the use of plates of different lengths (measured in a cross-sectional plane), which is uneconomical. Moreover. the sound absorption in such a device is not uniform throughout the cross-section, unless thev widths of the passages between the plates are so chosen that for each passage the ratio between the circumference, covered by sound absorbing material, of its cross-section and the area thereof has one and the same value. This is very dimcult to realize and, owing to the small length of the end plates, practically impossible. Consequently, the sound absorption in the short end' In order to obviate these drawbacks, it has.

already been proposed so to arrange a number of equally sized plates as to fill up, in crosssectional View, the inscribed quadrangle of the circular conduit. yThis arrangement, however,

has the disadvantage-ous feature that a relatively great part, viz. about 36% of the cross-sectional area of the conduit islocatedoutside said square, and is, therefore, to be considered as lost space.

If the gases should be allowed to vo'wthrough the four segmental passages outside the square, the sound waves would be propagated for the major part -therethrough and the sound deadening effect of the plates inside the square would hardly be noticeable. In view thereof, it is nec-y cssary to obturate said outer passages, but this causes the resistance to flow of the gases through the conduit to be increased by about 150%, since said resistance is proportional to the square of the gas velocity.

'Ihe object of the present invention, which also contemplates the use of equally sized sound absorbing plates, is to considerably reduce the lost space as compared with the varrangement just referred to. According to this invention, the

plates arel arranged in three groups, each of which occupies in cross-sectional view, a rhomb formed by two adjacent equilateral triangles of the inscribed regular hexagon, the plates of each group being parallel to one side of the rhomb 55 involved. In case of a conduit having an elliptical cross-section (which can be considered as the oblique projection of a circle), the regular hexagon is deformed into an irregular one, and the rhombs into parallelograms.

A sound deadener in accordance with the invention occupies about 83% of the cross-sectional area of the conduit, so that the increase of the resistance to iiow, as compared with the circular cross-section, is only 45%.

In the drawing:

Figs. l and 2 are an axial section and a crosssection, respectively, of one embodiment of the invention, the sections being taken on the line I-I` in Fig. 2 and on` the line II-II in Fig. 1, respectively,

Fig. 3 is a fragmentary side elevation of one of the sound absorbing plates illustrating the construction thereof, including the surrounding frame. v Y

Fig. 4 is a detail horizontal sectional view taken on the line IV-IV of Fig. 3.

Fig. 5 is a horizontal sectional view similar to Fig. 4, illustrating a modiiiedarrangement wherein the perforated plates are secured to the outer faces of the frame instead of to the inner faces as in Fig. 4.

Fig. 6 is a diagrammatic cross sectional view of a modiiled` form of the invention, illustrating its adaptation to an elliptical ilue or stack.

In view of the explanation given, Fig. 2 will hardly need further explanation. Extending between the wall of a cylindrical casing 6 and a' central column l, and at angular distances of 120, are three angle bars 8, 9, l0 mounted with their openings upward. Similar angle bars Il, I2, I3 extend parallel to the bars 9, l0, 8, respectively. Welded to each bar 8-I3 are ten short, horizontal, equally spaced angles lat-i311, each pair of opposed angles supporting a rectangular sound-absorbing plate p.

The outer ends of the bars 8|3 are the angular points of an inscribed regular hexagon. Consequently, all plates p-have the same length,

- so that the uniformity of their spacing ensures uniform absorption oi the sound throughout the cross-section. As stated, the lost space, i. e. the cross-sectional area between the sides of the hexagon and the casing wall, is relatively small. If said area is not obturated, each-of the segmental passages may accommodate a short sound-absorbing plate p (see Fig. 2)

The sound deadener illustrated comprises four vertically spaced units, the plates of each unit forming an angle of 60 with the adjacent plates of the adjacent unit. Obviously, the number of v said units may be varied according to circumstances.

Glass wool has proved to be very suitable as a material ,for the sound-absorbing plates. As plates of this material are rather brittle, they are preferably framed and covered by perforated metal sheets. Figs. 3 and 4 show such a construction, Fig. 4 being a section along the line IV-IV of Fig. 3. Plate p is covered on either side by perforated steel sheets Il, l5, which directly engage the material thereof.

The frame is composed of two parts, the one being formed of flat iron I6, the other of angle iron Il, said parts being interconnected by bolts i8. By means of lugs I9, the frame can be secured at? the offset ears 20 carried by horizontal strut According to Fig. 5, the plates I4, l5 are clamped to the outside of the frame I6, I1, so

that they do not directly engage the glass wool. Fig. 6 shows that the invention can as well be applied to a conduit having an elliptical crosssection. Obviously, all of the plates p have the spaced at plates of sound-absorbing material,

wherein the plates are arranged in three groups, each of which occupies, in cross-sectional view, a rhomb formed by two adjacent triangles of the inscribed regular hexagon, and wherein the plates oi each group are parallel to one side of the rhomb involved.

2l. A sound-deadener adapted to be accommodated in a gas conduit of elliptical cross-section and comprising a plurality of relatively narrowly spaced flat plates of sound-absorbing material, wherein the plates are arranged in three groups,

each of which occupies, in cross-sectional view,

the plates of each unit forming an angle of 60 with the adjacent plates of the adjacent unit.

4. A sound deadener for gas conduitsV of tubular cross section, comprising a plurality of plates of sound absorbing material disposed parallel to the axis of the conduit, said plates being supported in spaced relation in three groups vwithin the cross sectional area oi the conduit, and the plates of each group being arranged within a parallelogram formed by two adjacent triangles of an enscribed hexagon, said plates in each group being parallel to one side oi their related parallelogram.

HERMANNUS VAN TONGEREN. 

